AMC1210 Datasheet, PDF (18/47 Pages) Burr-Brown (TI) – Quad Digital Filter for 2nd-Order Delta-Sigma Modulator

AMC1210
SBAS372A – APRIL 2006 – REVISED OCTOBER 2006
100000
10000
1000
100
10
Sinc³
Sincfast
Sinc²
1
Sinc
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1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
Oversampling Ratio
Figure 14. Comparator Filter Resolution
The maximum resolution yields the peak values in Table 9 (15 bits binary, 32,768 decimal). Note that in order to
achieve the maximum value, the delta-sigma modulator is operated at absolute maximum positive or negative
full-scale, which is outside of the recommended full-scale range of 80% of most delta-sigma modulators.
Sinc Filter Unit
The AMC1210 utilizes a standard integration/decimation/differentiation scheme to achieve the sinc filter. It can
be configured as a Sinc¹, Sinc², Sinc³ or Sincfast filter with oversampling ratios (OSRs) continuously between 1
and 256. Figure 15 illustrates the frequency response of each type of filter.
1
(1)
SINC FILTER RESPONSE
0
-20
-40
-60
-80
-100
-120
0
0
312.5k
625k
937.5k
Frequency (Hz)
3
(1)
SINC FILTER RESPONSE
-20
-40
-60
-80
-100
-120
0
312.5k
625k
937.5k
Frequency (Hz)
NOTE:
(1)
f_DATA
=
312.5kHz
=
f_CLK
OSR
=
10MHz
32
0
-20
-40
-60
-80
-100
1562.5k
-120
0
0
-20
-40
-60
-80
-100
1562.5k
-120
0
2
(1)
SINC FILTER RESPONSE
312.5k
625k
937.5k
Frequency (Hz)
(1)
SINCFAST FILTER RESPONSE
312.5k
625k
937.5k
Frequency (Hz)
Figure 15. AMC1210 Frequency Responses with Various Sinc Filters
1562.5k
1562.5k
18
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